I have been working on a load with MK V Jap model using RL 22 at 84 GR. Load development was done with the Weatherby 1 fired (this rifle) neck sized brass and was going into 1/2-3/4" at 100 w/168 gr TTSX at 3.58.

Moved to the new virgin Nosler brass for hunting. Used the same load and it shot into 1 1/2-1 3/4" groups. I am going back to the Weatherby to confirm original.

This seems too much difference and was just checking with the experts to get their comments.

I have found that small changes can make a huge difference with TSXs. Have you checked case volume of each type of brass? My initial thought is that there's enough difference in case capacity that the same powder charge is producing a different pressure result thereby causing the different grouping. In my experience a less than 1.5% change in powder weight can cut the group size by half. So a shortcut might be in the new brass shooting a group with a grain lighter and a grain heaver charge and see what you get and adjust accordingly. Why change the brass with the good result?

LWD

I would highly recomend comparing case capacity with the two casings. I'll bet that there is alot more capacity to the weatherby brand brass. I shoot rem and wby brass and there is often a 1-1.5 grain diff. It would be my guess that using the same load with nosler brass would be like adding 1-1.5 grains of powder to the wby brass. I highly recomend you spend about $90 and get a chrono.....then match the speeds between the two...I'll bet things will come back to mornal.

I"m with kraky and LWD.

In a .270 Win, going from Winchester to Remingtion brass is equal to adding a full gain of powder pressure wise. Nosler brass has a reputation for being thick, like Remington brass. New vs. once fired again, throws in it's own set of variables.... I'd load some fired Weatherby brass for my hunting loads.

before you make judgement take your once fired nos brass and neck size it and try it again. Once the brass is fire formed to your chamber case capasitys should be alot closer then comparing new brass to your old fired and neck sized brass.

Thanks for the information gentlemen and looks like a concensus and that is even better. This is my first reloading for the Weatherby and have loaded for a few years with several other non-belted rounds and have not run into this problem. My plan was to work the load up with the once fired and then load the new brass with the load I selected. My bad it seems. Do have enough of the once fired to make the upcoming elk hunt so that will be the plan. Suppose I will use the new nosler loads for practice and then I will have a lot of once fired brass. Will then back off a few grains and start from scratch with the Nosler stuff which as said above should be closer in size to the Weatherby after firing and neck sizing. Guess there is a reason Weatheby charges so much for their brass.

Thanks again. Oh, yes I do have a Oehler so guess it is time to break it out as well.

muygrande,
Here is the difference in water volume that I came up with using .300 Win. mag., once fired brass :
Nosler 88.6 grs. of water
Norma 93 grs. of water
Just an illustration of volume differences (case capacity) for different brands of brass.
FWIW,
Jim

Thanks Jim and those are both once fired brass? That is a 5% higher capacity on the Norma.

To be certain with my CPA vs engineering mind this would translate into much higher pressure in the smaller case (Nosler) given that both are loaded with the same grains of the same powder with the same bullet, etc??

quote:

To be certain with my CPA vs engineering mind this would translate into much higher pressure in the smaller case (Nosler) given that both are loaded with the same grains of the same powder with the same bullet, etc??

Yes, alot more pressure.

Exactly, see pm.
Jim

Antelope and Jim, I certainly owe everyone who contributed on this one. Hope I can payback some day. Jim, thanks again for the great info on the pm, I am a beholdin to ya.

Someone much smarter than I said "when ya get too old to learn, may as well move on upstairs and start over". Certainly glad to still be a learnin!

Your welcome.

quote:

Here is the difference in water volume that I came up with using .300 Win. mag., once fired brass :
Nosler 88.6 grs. of water
Norma 93 grs. of water

Wow. That's more than I would have guessed. In light of that, I'll amend what I said. Start moving down in charge weights.

LWD

Keep in mind that I am talking about .300 Winchester magnum brass, not .300 Weatherby brass. There could be a difference and probably is. Maybe not as much variation, don't know. I was just trying to show that there IS a difference in case capacity between various brands of brass.
Jim

Went back to the Weatherby brass and whoola - right back to 1/2". Gonna just shoot up the nosler loads (35) and move on with a new workup with this brass.

Thanks again for the sharing of knowledge/experiences.

quote:

Originally posted by Jim Hundley:
muygrande,
Here is the difference in water volume that I came up with using .300 Win. mag., once fired brass :
Nosler 88.6 grs. of water
Norma 93 grs. of water
Just an illustration of volume differences (case capacity) for different brands of brass.
FWIW,
Jim

MUYGRANDE -

Norma lists data for "heavy" and "light" cases; as Antelopesniper pointed out, the heavier brass produces significantly greater pressure for a given amount of powder.

Below is Norma's data page on the 300 win. From there you can also click on the "Reloading: reloading data" tab to see their light/heavy loads.

http://www.norma.cc/content.as...k=Calibers&Title=300 Winchester Magnum



Hope this helps,

friar